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July 5, 1938.‘ J. w. MARDEN ET AL 2,123,015 _ SEAL FOR DISCHARGE LAMPS Filed April 1, 1936‘ [L17 INVENTOR J 14/. MJFDf/V 6'. NE/Ji' F. ATTORNE Patented July/'15, 1938 2,123,015 UNITED STATES PATENT OFFICE 2,123,015 SEAL FOR DISCHARGE LAMPS John Wesley Marden, East Orange, and George Meister, Newark, N. J., assignors, by mesne as signments, to Westinghouse Electric and Man ufacturing Company, East Pittsburgh, Pa... a corporation of Pennsylvania Application April 1, 1936, Serial No. 72,048 5 Claims. (Cl. 176-126) Our present invention relates to seals for elec ?ciency comparatively high currents must be tric apparatus and particularly electric discharge impressed upon the electrodes which necessitates apparatus wherein a discharge occurs between two electrodes in a gaseous atmosphere under comparatively high pressure. In the prior art leading-in conductors‘ for the device not only capable of carrying the necessary currents, but in various types of seals have been employed where- ' seal so that the high temperatures of operation of the device will not destroy the seal formed at the juncture of the leading-in conductors for the electrodes with the vitreous envelope. It is accordingly an object of our present in vention to provide a novel seal for electric devices in the leading-in ‘conductors for supplying the electrical energy to the electrodes or ?lament within the envelope are sealed through the Vitre 10 ous envelope. Moreover the problem of provid ing a seal such that the vcoemcient of expansion of the metallic leading-in conductor approxi particularly of the high pressure type employing mates that of the vitreous envelope so as to pre- a gaseous medium wherein the leading in con vent cracking of the seal with attendant loss of ductor forms an integral seal with the vitreous envelope of the device which will not be detri 15 ll the vacuum or gaseous medium has long been recognized. mentally aliected by the high temperatures of The customary construction has been to pro vide the leading-in conductor with a section of of the gaseous medium contained within the en a metal having an analogous co-emcient of ex 20 pansion to that of the vitreous envelope with the remainder of the leading-in conductor be ing of a less expensive metal or of a refractory operation of the device nor by the high pressure velope. Another object of our present invention is the 20 provision of a seal for a vitreous envelope or con tainer wherein the leading in conductor is sealed metal capable of withstanding high temperatures to the envelope in such manner as to provide an due to heating of the electrode or ?lament. How ever, with such construction that portion of the temperatures and pressures of operation of the 25 leading-in ‘conductor having the desired, co-ei integral seal capable of withstanding the high device and of carrying the requisite electrical ?cient of expansion has limited to a considerable extent the current carrying capacity of the lead currents during operation. ing-in conductor. provision of a seal for a vitreous envelope or con , In instances where the electric discharge de vice comprises a vitreous envelope provided with oppositely disposed electrodes between which a discharge occurs the electrodes are either heated to a thermionic emission from an exterior source or the electrodes are thermionically' heated by the discharge occurring between theeIectrodes upon the application of electrical energy thereto. In addition the envelope is usually provided with a gaseous medium comprising a metallic vapor, such for example as sodium, cadmium, mercury or the like at a substantial pressure ranging from a few millimeters of mercury to several atmospheres. Moreover as the pressure of the gaseous medium normally increases with 46 increase of temperature the provision of a suit able seal for the leading-in conductors presents an even more momentous problem than is pres ent with the usual incandescent lamp or electric device utilizing a vacuum. 50 additional’ such character as to form a perfect, We have previously shown and described in our copending application Serial No. 49,448, ?led November 13,v 1935, that the maximum e?‘lciency of a high pressure mercury vapor lamp is de pendent on the maximum wattage per centimeter 55 of arc length. _In order to obtain maximum ef Another object of our present invention is the tainer wherein the leading in conductor is pro 30 vided with a portion formed of thin metal hav~ ing a high melting point and due to its cross sectional area forms an integral seal with the en velope without the necessity of the seal forming portion being of the same coef?cient of expan sion as that of the envelope. Still further objects of our present invention will become readily apparentto those skilled in the art by reference to the accompanying draw 40 ing wherein, Figure l is a fragmentary view in cross-section of an electric discharge device particularly of the high pressure metal vapor type provided with a seal constructed in accordance with our pres 45 ent invention. Figure 2 is an enlarged cross-sectional view taken on the line 11-11 of Fig. 1. Figure 3 is a perspective view on an enlarged scale of a seal for electric discharge devices 0011- _ structed in accordance with our present inven tion, and Figure 4 is an elevational view partly in cross section showing the manner of constructing an electric discharge device of the metal vapor type 55 2 8,198,015 t employing seals in accordance with the teach ings of our present invention. , Referring now to the drawing in detail we have shown in Fig. l a vitreous envelope I constructed of hard glass, silica, or the like, but in instances with its respective electrode and ‘seal forming por-> , tion is inserted into the chamber lI‘and moved I downwardly of the chamber II until the upper electrode is positioned the desired distance from the lower electrode. The open end of the cham- - where the device is of the metallic vapor type ' ber II is then sealed as shown at II to thus hold the upper electrode and leading-in conductor in which is subjectable to high temperatures of op eration it is preferable to construct the container or envelope I of quartz due to its high melting 10 point. The envelope I is provided with a tubular extension I formed thereon during the sealing in process and embedded in the tubular portion is a leading-in conductor forming an integral seal with the tubular extension portion of the vit II reous container or envelope. The construction of this leading-in conductor may be better appre ciated by particular reference to Fig. 3 wherein the leading-in conductor comprises a substan~ tially cylindrical member 'I. This member may . , The vacuum pump (not shown) which is con nected to the chamber II is then operated to 10 evacuate the envelope I and the lower portion of the envelope I is suitably heated by flames II until the envelope attains a suitable fusing tem perature and at the same timethe vitreous core II- of the leading in conductor is also heated to II the fusion pointresulting in complete fusion of the core II with the envelope I both above and below the cylindrical metallic foil portion ‘I and also fusion of the core I l and envelope I occurs be formed of any suitable thin metal, such as through the longitudinal opening I provided in tungsten, tantalum, but preferably molybdenum the cylindrical metallic foil section ‘I until com plete fusion of the core II and envelope I results. thus completely embedding the leading-in con foil of about 1 mil thickness. This metal is formed into the con?guration of a cylinder by rolling and joining the overlapping ends and se curing the same in any suitable manner, such as by welding I. The cylindrical metallic foil member ‘I is pro vided with a longitudinal slot 9 for a purpose to be hereinafter more fully described and connected to this member 1 in any suitable manner, such as by welding, is an electrode III of suitable re fractory metal, such as tungsten, which may be provided with an additional refractory metal layer of coiled tungsten I2 with this portion being sub jected to the discharge between the oppositely disposed electrodes during operation of the device. Also connected to the cylindrical metallic foil portion is a rod like portion or wire II which may be formed of substantially U-shaped configura 40 tion having its ends secured as by welding to the metallic foil portion with the remaining portion of the wire II joined in a similar manner to the base of the U-shaped portion and constituting that portion of the leading in conductor adapted to be disposed exteriorly of the container or en velope I asshown more clearly in Fig. 1. Prior to connection of the exteriorly disposed portion II of the leading in conductor a core of vitreous material ll of the same composition as that of the vitreous envelope I is inserted in the cylindrical metallic foil portion ‘I of the leading in conductor thus conditioning the same for sealing in to the envelope ‘of the discharge device. This latter step may be accomplished in any suitable manner, but we find it expedient to employ the method and apparatus shown more particularly in Fig. 4. As the spacing between the electrodes of a dis charge lamp of the metal vapor type is an essen— tial factor in its efficiency of operation we first join the envelope I to a suitable vitreous chamber II and provide the opposite end of the envelope with a tubular member II having an elbow or the like II. The lower leading-in conductor as viewed from 65 Fig. 4, together with its electrode and seal form ing portion, as shown more particularly in Fig. 3, is then inserted into the chamber II while its upperend is open and such leading-in conductor slid downwardly of the chamber II and envelope 70 I until the extremity of the leading-in conductor ductOr and particularly the cylindrical metallic foil portion ‘I in the tubular portion I formed on the envelope I'during the fusion to form a com plete integral seal with the envelope. After the desired degree of evacuation of the envelope I is obtained and the appropriate gas eous medium or vapor forming metal is intro duced into the envelope I the ?ames I! are moved adjacent the upper seal forming portion where the same operation is performed to form the up per integral seal between the envelope I and the leading-in conductor particularly the cylindrical metallic foil portion 1. The envelope I and por tions II ofv the leading-in conductor are then severed from the chamber II and tubular mem ber II thus completing the device. It thus becomes obvious to those skilled in the art that we have provided a leading-in conductor particularly adaptable to electric discharge de vices subjectable to extremely high temperatures and pressures during operation wherein the lead ing-in conductor forms an integral‘seal with the vitreous envelope. Moreover, the seal forming portion being of comparatively thin metal or foil facilitates the radiation of heat which is gen erated by the resistivity thereof to the passage of the electric current thus obviating possibilities of cracking of the seal. While preferably the seal is formed of a metal having a coefllcient of expansion simulating that of the vitreous en velope it need not necessarily have such precise coemcient of expansion due to its being of com paratively thin cross section. In addition the area of cross-section of the cylindrical metallic foil portion of the leading-in conductor is such that the requisite electrical current can be readily supplied to the electrodes without danger of over heating. Although we have shown and described one specific embodiment of our invention we do not desire to be limited thereto as various other mod i?cations of the same may be made without de parting from the spirit and scope of the invention as set forth in the appended claims. What is claimed: rately positioning the leading in conductor and 1. The combination of a vitreous container, a conductor fused to a portion of said container 70 comprising a cylinder of metal foil, a leading in conductor secured to the wall of said cylinder electrode within the lower portion of the enve and extending exteriorly of said container, and rests against the shoulder portion I‘I thus accu lope I preparatory to the sealing in operation. II this desired position. Next the upper leading in conductor together an electrode within said container ‘having its ends connected to the periphery of said cylin- " 2,123,015 drical conductor and extending a substantial distance on the surface thereof in the direction of the longitudinal axis of said cylinder to form a support for said electrode. 2. The combination of a discharge device pro vided with an envelope of vitreous material, lead ing-in conductors comprising substantially cy lindrical members formed of‘metal foil having their interior and exterior surface fused to said 10 envelope to form a seal, leading-in conductors secured to the wall of each of said cylindrical members and extending exteriorly of said en velope, and electrodes within said envelope be tween which a discharge occurs when supplied 15 with electrical energy and subjectable to ex 3 discharge device having a vitreous envelope com prising a substantially cylindrical member of metal foil having a core of vitreous material readily fusible with the envelope of said discharge device to form an integral vacuum tight seal, an electrode having its ends connected to the pe riphery of said cylindrical member and extending a substantial distance on the outer surface in the direction of the longitudinal axis of said cylindrical member, and a wire having a bi 10 furcated end portion connected to the periphery of said cylindrical member and extending a sub stantial distance on the outer surface in the di- - rection of the longitudinal axis of said cylindrical member, and a wire having a bifurcated end por 15 tion connected to the periphery of said cylin drical member and extending a substantial dis tance on the outer surface thereof and extending tending a substantial distance on the surface exteriorly of the envelope of said discharge de 20 thereof in the direction of the longitudinal axis vice. 20 of said cylinder to form a support for each of said 5. A current conducting seal for an electric electrodes directly from said seals. discharge device having a vitreous envelope com 3. The combination of a discharge device pro prising a substantially cylindrical member of vided with an elongated envelope of vitreous metal foil having a longitudinal slot therein and 25 material, a leading-in‘ conductor disposed at op provided with a core of vitreous material of the 25 posite ends of said elongated envelope compris same composition as the envelope of said dis ing substantially a cylindrical member formed charge device and readily fusible with the lat of metal foil having a core of the same vitreous ter to entirely surround the cylindrical member material as said envelope to form a fused seal in and form an integral vacuum tight seal, an elec 30 tegral with the latter, a leading-in-conductor trode having its ends connected to the periphery secured to the wall of said cylindrical member of said cylindrical member and extending a sub 30 and extending exteriorly of said envelope, and stantial distance on the outer surface in the di an electrode disposed at each end of said en rection of the longitudinal axis of said cylindrical tremely high temperatures, each of said elec trodes having its ends connected to the periphery of the respective cylindrical member and ex velope between which a discharge occurs and 35 subjectable to extremely high temperatures, and each of said electrodes having their ends con nected to the periphery of the respective cylin drical member and extending a substantial dis tance 0n the outer surface thereof in the direc 40 tion of the longitudinal axis of said cylindrical member to form a support for each of said elec trodes directly from said seal. 4. A current conducting seal for an electric member, and a wire having a bifurcated end por tion connected to the periphery of_said cylindrical member and extending a substantial distance on the outer surface thereof, and the remaining portion of said Wire being coaxially disposed relative to the longitudinal axis of said cylin drical member and extending exteriorly of the 40 envelope of said device. JOHN WESLEY MARDEN. GEORGE MEIS'I'ER.